(19) |
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(11) |
EP 0 263 989 A3 |
(12) |
EUROPEAN PATENT APPLICATION |
(88) |
Date of publication A3: |
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21.12.1988 Bulletin 1988/51 |
(43) |
Date of publication A2: |
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20.04.1988 Bulletin 1988/16 |
(22) |
Date of filing: 15.09.1987 |
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(84) |
Designated Contracting States: |
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BE CH DE ES FR GB IT LI NL SE |
(30) |
Priority: |
16.09.1986 JP 21870886
|
(71) |
Applicant: KANEGAFUCHI KAGAKU KOGYO KABUSHIKI KAISHA |
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() |
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(54) |
Process for production of foamed molded articles of polypropylene resin |
(57) The present invention provides a process for production of foamed articles of a polypropylene
resin which comprises compressing pre-expanded beads of the propylene resin under
a gaseous pressure, filling a mold which can be closed but cannot be sealed with the
compressed beads, then venting the mold and heating and fusing the beads with steam
thereby producing the molded article in the shape of the mold. The process is characterized
in that pre-expanded beads of a polypropylene resin having two melting points when
measured by differential scanning calorimetry and having a quantity of the peak fusion
heat QH based on the melting point at the high temperature peak of the two melting
points of 0.3 to 3.5 cal/g are introduced into the mold at a compression rate is 10
to 60%. According to the present invention, foamed articles of polypropylene having
a minimized dimensional shrinkage rate (good dimensional accuracy) and excellent fusion
rate and surface appearance can be produced in high productivity.
